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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ding Y., Haskel D., Ovchinnikov S. G., Tseng Y. C., Orlov Y. S., Lang J. C., Mao H. K.
Заглавие : Novel pressure-induced magnetic transition in magnetite (Fe(3)O(4))
Разночтения заглавия :авие SCOPUS: Novel pressure-induced magnetic transition in magnetite (Fe3O4)
Место публикации : Phys. Rev. Lett.: AMER PHYSICAL SOC, 2008. - Vol. 100, Is. 4. - Ст.45508. - ISSN 0031-9007, DOI 10.1103/PhysRevLett.100.045508
Примечания : Cited References: 39
Предметные рубрики: MULTIPLE-SCATTERING THEORY
X-RAY DICHROISM
LOWER MANTLE
VERWEY TRANSITION
K-EDGE
CIRCULAR-DICHROISM
SPIN TRANSITION
BAND-STRUCTURE
IRON
FE
Ключевые слова (''Своб.индексиров.''): emission spectroscopy--magnetoelectronics--pressure effects--synchrotron radiation--diamond anvil cell--magnetic transition--x-ray magnetic circular dichroism--magnetite
Аннотация: Fe K-edge x-ray magnetic circular dichroism of magnetite (Fe(3)O(4)) powders was measured with synchrotron radiation under variable pressure and temperature conditions in diamond anvil cell. The magnetic dichroism was observed to decrease discontinuously by similar to 50% between 12 and 16 GPa, independent of temperature. The magnetic transition is attributed to a high-spin to intermediate-spin transition of Fe(2+) ions in the octahedral sites and could account for previously observed structural and electrical anomalies in magnetite at this pressure range. The interpretation of x-ray magnetic circular dichroism data is supported by x-ray emission spectroscopy and theoretical cluster calculations.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Myagkov V. G., Bayukov O. A., Bykova L. E., Zhigalov V. S., Bondarenko G. N.
Заглавие : Solid-state synthesis in Ni/Fe/MgO(001) epitaxial thin films
Место публикации :. - Vol. 80, Is. 7. - P.487-490. - ISSN 0021-3640, DOI 10.1134/1.1839296
Примечания : Cited References: 34
Предметные рубрики: HIGH-TEMPERATURE SYNTHESIS
BINARY DIFFUSION COUPLES
MARTENSITIC TRANSFORMATIONS
PHASE-FORMATION
MAGNETIC-PROPERTIES
SPIN DYNAMICS
INVAR-ALLOYS
IRON
TRANSITION
NUCLEATION
Аннотация: Solid-state synthesis in Ni/Fe/MgO(001) bilayer epitaxial thin films has been studied experimentally. The phase sequence Fe/Ni -- (similar to350degreesC)Ni(3)Fe -- (similar to400degreesC)NiFe -- (similar to550degreesC)gamma(par) is formed as the annealing temperature increases. The crystal structure in the invar region consists of epitaxially intergrown single-crystal blocks consisting of the paramagnetic gamma(par) and ferromagnetic NiFe phases, which satisfy the orientation relationship [100](001)NiFe parallel to [100](001)gamma(par). It has been shown that the nucleation temperatures of the Ni(3)Fe, NiFe, and gamma(par) phases coincide with the temperatures of solid-state transformations in the Ni-Fe system. (C) 2004 MAIK "Nauka/Interperiodica".
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Iskhakov R. S., Komogortsev S. V., Balaev A. D., Chekanova L. A.
Заглавие : Dimensionality of a system of exchange-coupled grains and magnetic properties of nanocrystalline and amorphous ferromagnets
Место публикации : JETP Letters. - 2000. - Vol. 72, Is. 6. - P.304-307. - ISSN 0021-3640, DOI 10.1134/1.1328443
Примечания : Cited References: 15
Предметные рубрики: RANDOM ANISOTROPY
FILMS
IRON
SIZE
Аннотация: Characteristics of random magnetic anisotropy in ferromagnetic films of amorphous Co90P10 and nanocrystalline Ni75C25 , Fe80B4C16 , and Co80C20 alloys and also in multilayer films [Co93P7(x)/Pd(14 Angstrom)](20) and [Co90P10(x)/Pd(14 Angstrom)](20) obtained by various technological procedures were studied experimentally. It was found that the spatial dimensionality (d) of the system of ferromagnetically coupled grains (2R(c)) in the materials under study determined the exponent in the power dependence of the approach of magnetization to saturation in the region of fields H 2A / MRc2. The dependence DeltaM similar to H-1/2 was observed for nanocrystalline and amorphous films with a three-dimensional grain arrangement. The approach to saturation in multilayer films with a two-dimensional grain arrangement in an individual magnetic layer follows the law DeltaM similar to H-1. The main micromagnetic characteristics of random anisotropy, such as the ferromagnetic correlation radius R-f and the average anisotropy [K] of a ferromagnetic domain with a size of 2R(f) , were determined for multilayer Co/Pd films. Correlation was found between the coercive field and these characteristics of random anisotropy. (C) 2000 MAIK "Nauka / Interperiodica".
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Popova E. A., Tristan N., Vasiliev A. N., Temerov V. L., Bezmaternykh L. N., Leps N., Buechner B., Klingeler R.
Заглавие : Magnetization and specific heat of DyFe3(BO3)(4) single crystal
Разночтения заглавия :авие SCOPUS: Magnetization and specific heat of DyFe 3(BO 3) 4 single crystal
Место публикации : Eur. Phys. J. B: SPRINGER, 2008. - Vol. 62, Is. 2. - P123-128. - ISSN 1434-6028, DOI 10.1140/epjb/e2008-00146-5
Примечания : Cited References: 18
Предметные рубрики: IRON
NDFE3(BO3)(4)
GDFE3(BO3)(4)
Ключевые слова (''Своб.индексиров.''): antiferromagnetic orders--iron subsystems--antiferromagnetic materials--dysprosium compounds--magnetic field effects--magnetization--specific heat--thermodynamics--single crystals
Аннотация: We present thermodynamic and magnetic studies of single crystalline DyFe3(BO3)(4). The data indicate an easy axis antiferromagnetic order below T-N similar to 38 K which we attribute to the Fe subsystem. The Dy subsystem remains paramagnetic down to the lowest investigated temperatures of 2 K, but it is polarized by the Fe spins due to a f-d interaction. External magnetic field leads to a spin-flop transition in the iron subsystem as well as to superposed magnetization in the Dy subsystem. The repopulation of two low-lying Kramers doublets in Dy3+ ions results in well defined Schottky anomalies in specific heat and magnetization.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Adem U., Wang L., Fausti D., Schottenhamel W., van Loosdrecht PHM, Vasiliev A., Bezmaternykh L. N., Buchner B., Hess C., Klingeler R.
Заглавие : Magnetodielectric and magnetoelastic coupling in TbFe3(BO3)(4)
Коллективы :
Разночтения заглавия :авие SCOPUS: Magnetodielectric and magnetoelastic coupling in TbFe3(BO 3)4
Место публикации : Phys. Rev. B: AMER PHYSICAL SOC, 2010. - Vol. 82, Is. 6. - Ст.64406. - ISSN 1098-0121, DOI 10.1103/PhysRevB.82.064406
Примечания : Cited References: 23. - We thank K. L. and S. G. for technical support. Work was supported by the DFG through Grants No. HE 3439/6 and No. 486 RUS 113/982/0-1.
Предметные рубрики: DIELECTRIC-CONSTANTS
IRON
GDFE3(BO3)(4)
MULTIFERROICS
TEMPERATURE
Аннотация: We have studied the magnetodielectric and magnetoelastic coupling in TbFe3(BO3)(4) single crystals by means of capacitance, magnetostriction, and Raman spectroscopy measurements. The data reveal strong magnetic field effects on the dielectric constant and on the macroscopic sample length which are associated to long-range magnetic ordering and a field-driven metamagnetic transition. We discuss the coupling of the dielectric, structural, and magnetic order parameters and attribute the origin of the magnetodielectric coupling to phonon mode shifts according to the Lyddane-Sachs-Teller relation.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Raikher Y. L., Stepanov V. I., Stolyar S. V., Ladygina V. P., Balaev D. A., Ishchenko L. A., Balasoiu M.
Заглавие : Magnetic properties of biomineral particles produced by bacteria Klebsiella oxytoca
Коллективы :
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 52, Is. 2. - P298-305. - ISSN 1063-7834, DOI 10.1134/S1063783410020125
Примечания : Cited References: 29. - This study was supported by the Russian Foundation for Basic Research (project nos. 07-02-96026, 07- 02-96017, and 08-02-00802) and performed within the framework of the Federal Target Program "Research and Research-Pedagogical Personnel of Innovation Russia for 2009-2013."
Предметные рубрики: FERRITIN
NANOPARTICLES
IRON
SUSCEPTIBILITY
FERRIHYDRITE
BEHAVIOR
FINS
Аннотация: Ferrihydrite nanoparticles (2-5 nm in size) produced by bacteria Klebsiella oxytoca in the course of biomineralization of iron salt solutions from a natural medium exhibit unique magnetic properties: they are characterized by both the antiferromagnetic order inherent in a bulk ferrihydrite and the spontaneous magnetic moment due to the decompensation of spins in sublattices of a nanoparticle. The magnetic susceptibility enhanced by the superantiferromagnetism effect and the magnetic moment independent of the magnetic field provide the possibility of magnetically controlling these natural objects. This has opened up the possibilities for their use in nanomedicine and bioengineering. The results obtained from measurements of the magnetic properties of the ferrihydrite produced by Klebsiella oxytoca in its two main crystalline modifications are reported, and the data obtained are analyzed theoretically. This has made it possible to determine numerical values of the magnetic parameters of real biomineral nanoparticles.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Frolov G. I., Bachina O. I., Zav'yalova M. M., Ravochkin S. I.
Заглавие : Magnetic properties of nanoparticles of 3d metals
Коллективы :
Место публикации : Tech. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2008. - Vol. 53, Is. 8. - P1059-1064. - ISSN 1063-7842, DOI 10.1134/S1063784208080136
Примечания : Cited References: 19. - This study was supported by the targeted program "Development of the Research Potential of Higher Education Institutions," grant no. RNP.2.1.1.7376.
Предметные рубрики: CLUSTERS
IRON
PARTICLES
Аннотация: The influence of size effects on the coercive force, magnetization, and Curie temperature in nanoparticles of 3d metals is considered. It is shown that experimental results obtained during the last two decades provide new information on peculiar magnetic properties of these particles.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Smirnova E. S., Alekseeva O. A., Dudka A. P., Verin I. A., Artemov V. V., Bezmaternykh L. N., Gudim I. A., Frolov K. V., Lyubutin I. S.
Заглавие : Structure of Gd0.95Bi0.05Fe3(BO3)4single crystals at 293 and 90 K
Место публикации : Crystallogr. Rep.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 61, Is. 4. - P.558-565. - ISSN 10637745 (ISSN), DOI 10.1134/S1063774516040192
Примечания : Cited References: 27. - This study was performed using the equipment of the Center of Collective Use of the Shubnikov Institute of Crystallography of the Russian Academy of Sciences and it was supported by the Ministry of Education and Science of the Russian Federation (Project RFMEFI62114X0005) and in part by the Russian Foundation for Basic Research (Grant nos. 14-02-00483 and 14-02-00307) and the Federal Program on Support of Leading Scientific Schools (Grant no. NSh-6617.2016.5).
Предметные рубрики: TRIGONAL GdFe3(BO3)4
PHASE-TRANSITIONS
IRON
Аннотация: The structure of GdFe3(BO3)4 single crystals has been studied by X-ray diffraction at 293 and 90 K. The crystals are grown from a flux in the Bi2Mo3O12–B2O3–Li2MoO4–Gd2O3–Fe2O3 system. The results of chemical analysis and structural study show that these crystals contain bismuth as an impurity. It is found that bismuth atoms are located at gadolinium sites in the structure. A decrease in the temperature is accompanied by a lowering of the symmetry from sp. gr. R32 (at 293 K) to sp. gr. P3121 (at 90 K). The presence of two types of iron chains with different geometries at 90 K promotes a change in the magnetic properties of these crystals with a decrease in the temperature. © 2016, Pleiades Publishing, Inc.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gavrichkov V. A., Polukeev S. I., Ovchinnikov S. G.
Заглавие : Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : Phys. Rev. B. - 2020. - Vol. 101, Is. 9. - Ст.094409. - ISSN 2469-9950, DOI 10.1103/PhysRevB.101.094409. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 65. - We acknowledge the support of the Russian Science Foundation through Grant No. 18-12-00022
Предметные рубрики: EXCHANGE INTERACTION
PHASE-TRANSITIONS
STATE
ELECTRON
IRON
Аннотация: We derived simple rules for the sign of 180° superexchange interaction based on the multielectron calculations of the superexchange interaction in the transition metal oxides that are valid both below and above spin crossover under high pressure. The superexchange interaction between two cations in dn configurations is given by a sum of partial contributions related to the electron-hole virtual excitations to the different states of the dn+1 and dn−1 configurations. Using these rules, we have analyzed the sign of the 180° superexchange interaction of a number of oxides with magnetic cations in electron configurations from d2 until d8: the iron, cobalt, chromium, nickel, copper, and manganese oxides with increasing pressure. The most interesting result concerns the magnetic state of cobalt and nickel oxides CoO, Ni2O3 and also La2CoO4, LaNiO3 isostructural to well-known high-TC and colossal magnetoresistance materials. These oxides have a spin 12 at the high pressure. Change of the interaction from antiferromagnetic below spin crossover to ferromagnetic above spin crossover is predicted for oxide materials with cations in d5(FeBO3) and d7(CoO) configurations, while for materials with the other dn configurations spin crossover under high pressure does not change the sign of the 180∘ superexchange interaction.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kremneva A. M., Fedorov A. V., Bulavchenko O. A., Knyazev Yu. V., Saraev A. A., Yakovlev V. A., Kaichev V. V.
Заглавие : Effect of calcination temperature on activity of Fe2O3-Al2O3 nanocomposite catalysts in CO oxidation
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [17-73-20157]; National center of investigation of catalysts" at Boreskov Institute of Catalysis
Место публикации : Catal. Lett. - 2020. - Vol. 150. - P.3377-3385. - ISSN 1011-372X, DOI 10.1007/s10562-020-03250-8. - ISSN 1572-879X(eISSN)
Примечания : Cited References: 31. - This work was supported by the Russian Science Foundation (Grant No. 17-73-20157). The experiments were performed using facilities of the shared research center "National center of investigation of catalysts" at Boreskov Institute of Catalysis. The authors thank A.Yu. Gladky for the TPR measurements and Z.S. Vinokurov for the XRD measurements.
Предметные рубрики: MOSSBAUER
SPECTROSCOPY
CHEMISTRY
IRON
XPS
ADSORPTION
OXYGEN
FE
Аннотация: Nanocomposite Fe–Al oxide catalysts were prepared by the melting of iron and aluminum nitrates with the subsequent calcination in air at different temperatures. It was found that the catalysts calcined at 450 °C are more active in the oxidation of CO than the catalysts calcined at 700 °C. X-ray diffraction and X-ray photoelectron spectroscopy showed that all the catalysts consist of hematite, α-Fe2O3 nanoparticles, and Al2O3 in an amorphous state. Iron oxide is the active component, which provides the oxidation of CO, while alumina is a texture promoter. The increase in the calcination temperature leads to a minor increase in the average size of hematite nanoparticles and an insignificant decrease in the specific surface area. Kinetic measurements showed that the oxidation of CO over the Fe–Al catalysts calcined at 450 and 700 °C proceeds with the activation energy of 61–69 and 91 kJ/mol, respectively. This means that the low-temperature and high-temperature catalysts contain different active species. Temperature-programmed reduction with CO indicated that the decrease in the calcination temperature improves the reducibility of the Fe-Al nanocomposites. According to 57Fe Mössbauer spectroscopy, the low-temperature catalysts contain hydrated iron oxides (acagenite and ferrihydrite) and a significant amount of highly defective hematite, which is absent in the high-temperature catalyst. These species can provide the enhanced activity of the low-temperature catalysts in the oxidation of CO.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Grishina, Svetlana, Kodera, Peter, Goryainov, Sergey, Oreshonkov A. S., Seryotkin, Yurii, Simko, Frantisek, Polozov, Alexander G.
Заглавие : Application of Raman spectroscopy for identification of rinneite (K3NaFeCl6) in inclusions in minerals
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [18-05-00682]; European Regional Development FundEuropean Union (EU) [ITMS 26240220086]; Vedecka Grantova Agentura MSVVaS SR a SAV [1/0313/20]
Место публикации : J. Raman Spectrosc. - 2020. - Vol. 51, Is. 12. - P.2505-2516. - ISSN 0377-0486, DOI 10.1002/jrs.6005. - ISSN 1097-4555(eISSN)
Примечания : Cited References: 55. - Russian Foundation for Basic Research, Grant/Award Numbers: 18-05-00682, 18-05-00682; European Regional Development Fund, Grant/Award Number: ITMS 26240220086; Vedecka Grantova Agentura MSVVaS SR a SAV, Grant/Award Number: 1/0313/20
Предметные рубрики: SALT MELT
IRON
DEPOSIT
FLUIDS
TRANSFORMATIONS
FERRIHYDRITE
Аннотация: Solid daughter phases in fluid and salt melt inclusions in minerals provide important clues to characterization of mineral‐forming processes. The analysis of the fluid inclusions often requires the exposure of the daughter minerals. Rinneite (K3NaFeCl6), which is a hygroscopic mineral, decomposes in air and cannot thus be identified by conventional methods. A combined approach has been applied for investigation of synthetic and natural rinneite to acquire its diagnostic Raman spectrum for a nondestructive identification. We used natural rinneite inclusions in halite, suitable for applying a complex of methods, to clear up the reference spectrum. Improved high‐resolution X‐ray diffraction (XRD) data obtained from natural rinneite inclusion are comparable with that of previously published, with similar unit cell dimensions. Polarized Raman spectra of natural inclusions were obtained using different geometries and polarization of the incident and scattered light. Interpretation of experimental Raman spectra was performed within the framework of lattice dynamics simulations and group analysis. Individual spectral bands are interpreted in terms of Raman‐active vibrational modes of K3NaFeCl6 structural units. Raman spectrum of synthetic rinneite with main peaks at 75, 91, 103, 143, 167, 171, 187, and 239 cm−1 agrees well with the spectra of rinneite inclusions in halite from the Nepa potash deposit and rinneite daughter minerals in salt melt inclusions hosted by quartz veinlets from the porphyry gold systems in the Central Slovakia Volcanic Field. This provides a firm basis for any future identification of this mineral worldwide, using nondestructive Raman spectroscopy.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'min V. I., Orlov Yu. S., Zarubin A. E., Ovchinnikova T. M., Ovchinnikov S. G.
Заглавие : Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model
Коллективы : Russian Scientific FoundationRussian Science Foundation (RSF) [18-12-00022]
Место публикации : Phys. Rev. B. - 2019. - Vol. 100, Is. 14. - Ст.144429. - ISSN 2469-9950, DOI 10.1103/PhysRevB.100.144429. - ISSN 2469-9969(eISSN)
Примечания : Cited References: 72. - The authors thank the Russian Scientific Foundation for the financial support under Grant No. 18-12-00022.
Предметные рубрики: LOWER-MANTLE
STATE
TRANSITION
PRESSURE
IRON
SUSCEPTIBILITY
Аннотация: To study non-Heisenberg effects in the vicinity of spin crossover in strongly correlated electron systems we derive an effective low-energy Hamiltonian for the two-band Kanamori model. It contains a Heisenberg high-spin term proportional to exchange constant as well as a low-spin term proportional to spin gap parameter ɛs. Using cluster mean field theory we obtain several non-Heisenberg effects. Near the critical value of spin gap ɛcs there is a magnetic phase transition of first order. In the vicinity of ɛcs in the paramagnetic phase we observe nontrivial behavior of the Curie constant in the paramagnetic susceptibility in the wide range of temperature. Reentrant temperature behavior of nearest-neighbor spin-spin correlations is observed at ɛsɛcs. Finally, the pressure-temperature magnetic phase diagram for ferroperriclase is obtained using the effective Hamiltonian.
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Togushova, Yu. N., Shestakov V. A., Korshunov M. M.
Заглавие : Impurity-induced smearing of the spin resonance peak in Fe-based superconductors
Коллективы : RFBR [13-02-01395]; President Grant for Government Support of the Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; Ministry of education and science of Russia [GF-2, SFU]
Место публикации : J. Low Temp. Phys.: Springer/Plenum Publishers, 2016. - Vol. 185, Is. 5-6. - P.481-487. - ISSN 0022-2291, DOI 10.1007/s10909-016-1577-x. - ISSN 1573-7357(eISSN)
Примечания : Cited References:25. - We acknowledge partial support by the RFBR (Grant 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), and The Ministry of education and science of Russia (GF-2, SFU).
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
ELECTRONIC-STRUCTURE
IRON
Ключевые слова (''Своб.индексиров.''): fe-based superconductors--spin resonance peak--spin-orbit coupling--impurity scattering
Аннотация: The spin resonance peak in the iron-based superconductors is observed in inelastic neutron scattering experiments and agrees well with predicted results for the extended s-wave (s±) gap symmetry. On the basis of four-band and three-orbital tight-binding models we study the effect of nonmagnetic disorder on the resonance peak. Spin susceptibility is calculated in the random-phase approximation with the renormalization of the quasiparticle self-energy due to the impurity scattering in the static Born approximation. We find that the spin resonance becomes broader with the increase of disorder and its energy shifts to higher frequencies. For the same amount of disorder the spin response in the s± state is still distinct from that of the s++ state.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Pavlovskiy M. S., Zinenko V. I., Shinkorenko A. S.
Заглавие : Effect of a rare-earth ion on the structural instability in RFe3(BO3)4 crystals
Коллективы : Russian Science Foundation [17-72-10122]
Место публикации : JETP Letters. - 2018. - Vol. 108, Is. 2. - P.116-120. - ISSN 0021-3640, DOI 10.1134/S0021364018140114. - ISSN 1090-6487(eISSN)
Примечания : Cited References: 17. - This work was supported by the Russian Science Foundation (project no. 17-72-10122).
Предметные рубрики: Iron
GdFe3(BO3)4
Аннотация: The dynamics of the crystal lattice of RFe3(BO3)4 (R = Pr, Nd, Sm, Gd, Tb, Dy, and Ho) compounds in the high-symmetry R32 phase has been calculated. Significant changes in spectra of compounds with various rare-earth ions have been obtained only near the edge Λ point of the Brillouin zone (qΛ = 1/3(−2b1 + b2 + b3, where b1, b2, and b3 are the reciprocal lattice vectors) for acoustic oscillation branches. A decrease in the frequency of an acoustic mode at the point Λ has been revealed in all studied compounds. This frequency depends on the type of rare-earth ion and decreases from a compound with Pr to a compound with Ho down to imaginary values. Such a behavior of the frequency of the unstable acoustic mode is in good agreement with experimental data on the dependence of the temperature of the R32 → P3121 structural phase transition on the type of rare-earth ion in ferroborates.
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15.

Вид документа : Статья из сборника (выпуск монографической серии)
Шифр издания :
Автор(ы) : Igumenov, A. Yu, Parshin A. S., Kanzychakova V. O., Demin A. M., Andryushchenko T. A., Mikhlin, Yu L., Pehelyakov O. P., Zhigalov V. S.
Заглавие : Factor analysis of inelastic electron scattering cross section spectra of FeSi2
Коллективы : International Scientific Conference Reshetnev Readings
Место публикации : IOP Conf. Ser.: Mater. Sci. Eng. - 2019. - Vol. 467: 21st International Scientific Conference Reshetnev Readings-2017. - Ст.012010. - , DOI 10.1088/1757-899X/467/1/012010
Примечания : Cited References: 21
Предметные рубрики: ENERGY-LOSS SPECTROSCOPY
IRON
Аннотация: Iron disilicide is widely used in creation of such nanotechnology devices as photoelectric converters. The investigation of iron silicide FeSi2 with the method of inelastic electron scattering cross-section spectroscopy was carried out. The decomposition of inelastic electron scattering cross-section spectra of FeSi2 to bulk and surface energy loss components using factor analysis was carried out. The amplitude of energy loss components can be used for identification of their origin.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Gerasimova Y. V., Vtyurin A. N., Gudim, I. A., Shestakov N. P., Ivanenko A. A.
Заглавие : Infrared absorption spectrum of HoFe3(BO3)4 crystal
Коллективы : RFBR [13-02-00825, 13-02-98041, SS-4828.2012.2]
Место публикации : Vib. Spectrosc.: Elsevier Science, 2014. - Vol. 72. - P.20-25. - ISSN 0924-2031, DOI 10.1016/j.vibspec.2014.02.005. - ISSN 1873-3697
Примечания : Cited References: 18. - The work was partially supported by the RFBR through Grants No. 13-02-00825 and 13-02-98041, SS-4828.2012.2.
Предметные рубрики: MAGNETOELASTIC INTERACTIONS
IRON
GDFE3(BO3)4
Ключевые слова (''Своб.индексиров.''): holmium ferroborate--infrared absorption
Аннотация: Infrared (IR) absorption spectra of HoFe3(BO3)4 crystal have been obtained in spectral range 30–7000 cm−1 at temperatures from 4 to 423 K. Vibrational frequencies have been simulated with ‘Lady’ software package both for high-temperature and low-temperature phases. The experimental spectra have been analyzed on the basis of calculated data, and interpreted within the framework of internal vibrations of ionic complexes of HoFe3(BO3)4 crystal lattice. The spectral range under study was observed to have no Davydov splitting of internal vibrational modes due to unit cell multiplication. No effects of magnetic ordering on the IR spectra of the crystal under study were observed in the low-temperature range.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Korshunov M. M., Efremov D. V., Golubov A. A., Dolgov O. V.
Заглавие : Unexpected impact of magnetic disorder on multiband superconductivity
Коллективы : Dynasty Foundation; ICFPM; Ministry of Education and Science of the Russian Federation [14Y26.31.0007]; RFBR [12-02-31534, 13-02-01395]; Leading Scientific Schools of the Russian Federation [NSh-2886.2014.2]; DFG [1458]; EU-Japan
Место публикации : Phys. Rev. B: American Physical Society, 2014. - Vol. 90, Is. 13. - ISSN 1098-0121, DOI 10.1103/PhysRevB.90.134517. - ISSN 1550-235X
Примечания : Cited References: 41. - The authors are grateful to S.-L. Drechsler, P.J. Hirschfeld, K. Kikoin, and S.G. Ovchinnikov for useful discussions. We acknowledge partial support by the Dynasty Foundation and ICFPM (MMK), the Ministry of Education and Science of the Russian Federation (Grant No. 14Y26.31.0007), RFBR (Grant Nos. 12-02-31534 and 13-02-01395), President Grant for Government Support of the Leading Scientific Schools of the Russian Federation (NSh-2886.2014.2), DFG Priority Program 1458, and FP7 EU-Japan program IRON SEA.
Предметные рубрики: HIGH-TEMPERATURE SUPERCONDUCTIVITY
PARAMAGNETIC IMPURITIES
IRON
CONDUCTIVITY
ALLOYS
Аннотация: We analyze how the magnetic disorder affects the properties of the two-band s± and s++ models, which are the subject of discussions regarding iron-based superconductors and other multiband systems like MgB2. We show that there are several cases when the transition temperature Tc is not fully suppressed by magnetic impurities in contrast to the Abrikosov-Gor'kov theory, but a saturation of Tc takes place in the regime of strong disorder. These cases are: (1) the purely interband impurity scattering and (2) the unitary scattering limit. We show that in the former case the s± gap is preserved, while the s++ state transforms into the s± state with increasing magnetic disorder. For case (2), the gap structure remains intact.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Anshits A. G., Bayukov O. A., Anshits N. N., Pletnev O. N., Rabchevskii E. V., Vereshchagin S. N., Kondratenko E. V.
Заглавие : Nature of the active sites of ferrospheres in the oxidative condensation of methane
Коллективы : Russian Science Foundation [4-13-00289], Russian Congress on Catalysis (2; 2014 ; Oct. ; 2–5; Samara)
Место публикации : Kinet. Catal.: MAIK Nauka-Interperiodica / Springer, 2015. - Vol. 56, Is. 4. - P.523-531. - ISSN 0023, DOI 10.1134/S0023158415040023. - ISSN 16083210(eISSN)
Примечания : Cited References:37. - This work was supported by the Russian Science Foundation (grant no. 14-13-00289).
Предметные рубрики: GLASS CRYSTAL CATALYSTS
HIGH-TEMPERATURE
MOSSBAUER
MAGNETITES
MICROSPHERES
SELECTIVITY
CONVERSION
FERRITES
ASHES
IRON
Ключевые слова (''Своб.индексиров.''): oxidative condensation of methane--ferrospheres--iron spinel--mossbauer spectroscopy--structural defects
Аннотация: The catalytic properties of ferrospheres containing 76–97 wt % Fe2O3 in the oxidative condensation of methane were compared with their phase composition and the distribution of iron cations over the crystallographic positions of iron-containing phases in a steady state. It was established that the reaction route of methane oxidation changed at a Fe2O3 content of 89 wt %. Deep oxidation was the main reaction route on ferrospheres with a Fe2O3 content of 88.8 wt %. At a Fe2O3 content of ≥89 wt %, the yield of C2 hydrocarbons sharply increased and the contribution of deep oxidation decreased. The yield of C2 hydrocarbons correlated with the amount of defects in the structure of iron spinel, which are iron ions with the tetrahedral cation of Ca2+ and the octahedral cation vacancy among the nearest neighbors.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Yakushkin S. S., Dubrovskiy A. A., Balaev A. D., Shaykhutdinov K. A., Bukhtiyarova G. A., Martyanov O. N.
Заглавие : Magnetic properties of few nanometers ɛ-Fe2O3 nanoparticles supported on the silica
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 111, Is. 4. - Ст.44312. - ISSN 0021-8979, DOI 10.1063/1.3686647
Примечания : Cited References: 27. - authors thank A. D. Balaev and N. V. Volkov for fruitful discussions and comments. This work was supported by Program of RAS No. 27.46.
Предметные рубрики: HIGH-TEMPERATURE
IRON
STABILIZATION
OXIDE
GEL
Аннотация: Magnetic properties of ɛ-Fe2O3nanoparticles supported on silica with the average size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs are investigated. The investigation of the temperature behavior of magnetization within the temperature range from 4.2 to 1000 K revealed the presence of several magnetic subsystems in the species under study. The temperatures’ behavior of the magnetic moment value indicates ferrimagnetic ordering in the ɛ-Fe2O3nanoparticles with a Curie temperature of about 800 K and points to the existence of a significant paramagnetic contribution becoming apparent at low temperatures. According to the electron spin resonance data, the particles possess superparamagnetic behavior at temperature higher ∼120 K. The model of the magnetic structure of monophase system of few nanometers ɛ-Fe2O3nanoparticles supported on silica is proposed.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Tarasov A. S., Eremin E. V., Eremin A. V., Varnakov S. N., Ovchinnikov S. G.
Заглавие : Frequency-dependent magnetotransport phenomena in a hybrid Fe/SiO2/p-Si structure
Место публикации : J. Appl. Phys.: American Institute of Physics, 2012. - Vol. 112, Is. 12. - Ст.123906. - ISSN 0021-8979, DOI 10.1063/1.4769788
Примечания : Cited References: 31. - This study was supported by the Russian Foundation for Basic Research, Project No. 11-02-00367-a; the Presidium of the Russian Academy of Sciences, program Quantum Mesoscopic and Disordered Structures, Project No. 20.8; the Division of Physical Sciences of the Russian Academy of Sciences, program Spin Phenomena in Solids Nanostructures and Spintronics, Project No. II.4.3; the Siberian Branch of the Russian Academy of Sciences, Integration Projects Nos. 85 and 102, and the Federal target program Scientific and Pedagogical Personnel of Innovative Russia (State Contract No. NK-556P_15).
Предметные рубрики: SILICON
IRON
SPINTRONICS
PAIRS
Аннотация: We report the large magnetoimpedance effect in a hybrid Fe/SiO2/p-Si structure with the Schottky barrier. The pronounced effect of magnetic field on the real and imaginary parts of the impedance has been found at temperatures 25-100K in two relatively narrow frequency ranges around 1 kHz and 100MHz. The observed frequency-dependent magnetotransport effect is related to the presence of localized "magnetic" states near the SiO2/p-Si interface. In these states, two different recharging processes with different relaxation times are implemented. One process is capture-emission of carriers that involves the interface levels and the valence band; the other is the electron tunneling between the ferromagnetic electrode and the interface states through SiO2 potential barrier. In the first case, the applied magnetic field shifts energy levels of the surface states relative to the valence band, which changes recharging characteristic times. In the second case, the magnetic field governs the spin-dependent tunneling of carriers through the potential barrier. The "magnetic" interface states originate, most likely, from the formation of the centers that contain Fe ions, which can easily diffuse through the SiO2 layer. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769788]
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